Born Lynn Freyse in Detroit, Michigan, to Bill (1898–1969) and Evelyn S. Freyse (1908–2003), her family moved to Cleveland, Ohio, and later Tucson, Arizona, in hopes of coping with her mother's health needs, which required a warm, dry climate. She had a brother, Steve. Lynn's father, a Detroit native, was a Cartoonist who drew the classic comic strip and panel cartoon Our Boarding House from 1939 until his death thirty years later. The strip, syndicated by Newspaper Enterprise Association, ended its run in 1984.

Lynn was enrolled by her mother in acting classes as a way to overcome the child's natural bashfulness. The training helped her to land the better parts in class plays and some small roles in Western films shot in Arizona. She won scholarships as the 1957 Miss Arizona and then as a contestant in the 1958 Miss America pageant.

She married Chris Borden in 1958, but the couple later divorced in 1963 keeping his surname professionally. In 1982, she wed Roger Brunelle, and they remained married until her death.

After college, she relocated to San Francisco and secured a small, credited part on the ABC series, Hawaiian Eye. Her first role was uncredited as a party guest in Days of Wine and Roses (1962). The next year she had another uncredited part as a bus Passenger in David Janssen's ABC drama, The Fugitive. Following the cancelation of Hazel, after 4 seasons, in 1965 by NBC, the show was picked up by CBS for one final season. CBS made cast changes to the show and Borden was selected for the role of Barbara Baxter opposite Ray Fulmer as her television husband, Steve Baxter. Borden's role came to an end after one season when Hazel ended its run in 1966.

Borden was a collector of frog and elephant figurines. The interest in frogs came from her 1972 film role, when fans gave her frog figures after the premiere of Frogs at the Rialto Theater in Atlanta, Georgia. She stated, "I love frogs. They're cute, they won't harm you, and they're good luck. You know, kiss the frog and marry a Prince, that kind of thing. If I see a frog, real or otherwise, I'll always stop to look at it. ..."

Borden appeared in Walking Tall (1973) and the low-budget horror film Frogs (1972), about a town overrun by amphibians and reptiles. Other film appearances include Bob & Carol & Ted & Alice (1969), Black Mama White Mama (1973), Breezy (1973), Dirty Mary, Crazy Larry (1974), Savannah Smiles (1982) and Hellhole (1985). She has made guest appearances on such television series as My Three Sons, The F.B.I., Family Affair (twice), Ironside, Get Smart, The Mod Squad, Petrocelli, McMillan and Wife, Starsky and Hutch, Fantasy Island, The Fall Guy and CSI: NY. In her later years, Borden worked in commercials and plays.

She lost to Marilyn Van Derbur of Colorado but was nevertheless a preliminary swimsuit winner and a Top 10 semi-finalist. She enrolled at the University of Arizona–Tucson, where she earned a Bachelor of Arts degree in theater. During this time, she performed theater work in Tucson, and garnered small parts in movies (primarily Westerns that were shot in the area.

On March 3, 2015, Lynn Borden died in Encino, California, three weeks before her 78th birthday, following an extended illness.